MacTCP

MacTCP was the standard TCP/IP implementation for the Macintosh operating system through version 7.5.1. It was the first application-independent implementation of a TCP stack for a non-Unix platform and predates Winsock by over 5 years. Released in 1988, it is considered obsolete and has reliability issues and incomplete features that sometimes prevent it from operating properly on the modern Internet. In addition, the API was unique to the Mac OS, and at least one developer released a Berkeley Sockets-derived API to make porting from other platforms easier.